Objectives: 1. Research and work of the past three years has resulted in the refinement of a computer-controlled language training system. Through use of that system we have evidence that a young female chimpanzee (Pan; Lana, now 4 yrs old) has mastered a variety of linguistic-type skills--reading, sentence-completion, object naming, color naming, ability to engage in the exchange of novel sentences as used in conversation, ability to use sentences in response to the challenge of new problematic contexts, ability to request the names of things and then to use those names forthwith to request that they be given to her, etc. The mastery of these skills by this chimpanzee subject leads us to conclude that the system, with appropriate modifications, might be applied to the study of language processes of mentally retarded children with language deficits. 2. It is proposed that the present computer be moved to the Georgia Retardation Center for studies that will assess the feasibility of using the language-training system with mentally retarded children and, that contingent upon the success of those studies, that the system be expanded in Year 3. It is further proposed that work be undertaken at the Yerkes Primate Center in Year 1 to extend the capabilities of the present system for research with two groups of chimpanzees to assess the contributions of diverse experiences to the acquisition of language- relevant skills. 3. Studies of language-learning processes in mentally retarded children, the development of and studies with a portable language-training unit (the Conversation Board), continued studies with the present chimpanzee subject (Lana), and a systematic study with two groups of chimpanzees (N equals 8, total) to better understand the contributions of various experiences to language acquisition and to assess the potential of the ape as an animal model for linguistic research.